Four fertility traits were evaluated: #
- Cow pregnancy rate (CRj)
- Heifer pregnancy rate (CRk)
- Days in postpartum interval (PP) – the time interval between first calving and first insemination.
- Days open (OMC) – the time interval between first calving and subsequent conception.
The CRj and CRk indicators are defined as CR = 100 / the number of inseminations from the first to the successful one. If the series consisted of more than 15 procedures or none of the procedures were marked as successful, then CR = 100/16.
| Trait | CRj | CRk | PP | OMC |
| CRj | 0,027 | 0,483 | 0,581 | -0,012 |
| CRk | 0,056 | 0,025 | 0,024 | 0,022 |
| PP | -0,003 | 0,043 | 0,053 | 0,713 |
| OMC | -0,005 | -0,215 | 0,609 | 0,080 |
Model #
Wartości hodowlane cech płodności oszacowano metodą BLUP – wielocechowy model zwierzęcia, uwzględniając w modelu liniowym następujące wpływy:
- dla CRj i CRk: stały efekt miesiąca inseminacji, stałą regresję na wiek pierwszej inseminacji, losowy efekt stada-roku pierwszej inseminacji, addytywny efekt zwierzęcia,
- dla PP i OMC: stałe efekty stada-roku i miesiąca ocielenia oraz regresja na wiek krowy przy ocieleniu,
Wartości hodowlane dla wszystkich cech wyrażono jako odchylenia od średniej bazy, a następnie przekształcono na zmienną o średniej 100 i odchyleniu standardowym 10. Dla CRj i CRk wyższa wartość hodowlana buhaja oznacza, że przeciętnie na skuteczne unasienienie jego córek przypada mniej zabiegów inseminacyjnych. Wyższa wartość hodowlana buhaja pod względem OMC lub PP oznacza krótsze odstępy międzyocieleniowe lub przestoje poporodowe córek.
Genetic base #
The genetic base is the average breeding value of bulls born between 2009-2011, evaluated based on at least 50 daughters from at least 30 herds.
Repeatability of evaluation #
The repeatability (accuracy) of the evaluation was calculated using an approximation for the multivariate method BLUP animal model.
Conditions for accepting the evaluation #
The condition for accepting and publishing breeding values for fertility traits is that the evaluation is based on at least 10 daughters.
Fertility traits sub-index #
The fertility sub-index PI_FERTILITY:
PI_FERTILITY = 0.70 × CRj + 0.10 × CRk + 0.10 × PP + 0.10 × OMC
The fertility sub-index is standardized to a mean of 100 and a standard deviation of 10.
The fertility sub-index includes the breeding value for CRj (based on at least 10 effective daughters) and for CRk, PP, and OMC (evaluated with a repeatability of at least 0.10). Since a direct evaluation of these traits is not possible for young bulls, their breeding values are estimated using a multivariate model that allows for obtaining breeding values based on known genetic correlations. In this case, the breeding values of these traits, which are not recognized as official due to low accuracy (less than 10 daughters), are still used to calculate the fertility sub-index.
The sub-index is calculated based on international evaluations. If a bull does not have an international evaluation for a particular trait but a national evaluation is available, the sub-index is calculated entirely based on the national evaluation.